Cryogenic storage container with inflatable jacket insulation



Feb. 16, 1965 D. H. BLACK CRYOGENIC STORAGE CONTAINER WITH INFLATABLE JACKET INSULATION 2 Sheets-Sheet 1 Filed March 12, 1963 FIG.

PIC-3.3

.DOLPHUS H. BLACK,

INVENTOR. @UZZQN A T TORNE YS Feb. 16, 1965 D. H. BLACK 3,169,379

CRYOGENIC STORAGE CONTAINER wrm INFLATABLE JACKET msuuu-xou Filed March 12, 1965 2 Sheets-Sheet 2 FIG.5

DOLPHUS H. BLACK, INVENTOR.

A T TORNEYS United States Patent Ofiflce 3,,lb9,379 Patented Feb. 16, 1%65 3,169,379 CRYQGENIfi STURAGE CONTAINER WITH INFLATABLE JACKET INSULATION Bolphus H. Black, Rte. 1, Arab, Ala. Filed Mar. 12, 19-53, Ser. No. 264,730 17 tllaims. Cl. 62-59) (Granted under Title 35, US. (lode (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to containers for storing liquified gases and more particularly storage containers for use in outer space that are insulated by a light, highly flexible, inflatable jacket that is unrolled into an operating position by the gases released from the container.

In apparatus used for storing or handling liquifled gases having boiling point temperatures below 273 degrees Kelvin, it is common practice to surround the container or conduit, which directly contacts the liquid being contained, with a surrounding wall spaced from the inner container or conduit to form an insulating space. Such insulating space is generally provided with insulation consisting of finely divided particles of low heat conductivity, or such space is connected to a source of vacuum, or, in some instances, both are incorporated. Although such constructions are thermally eflicient they present the disadvantages of being bulky, heavy in weight, and relatively expensive to construct.

Furthermore, under certain conditions this additional bulk and weight associated with a standard insulated container cannot be tolerated. Such an instance is involved when the containers are to be used as tankers or propellant storage facilities for refueling space vehicles by the rendezvous technique. As is well known, this rendezvous technique of refueling requires that the filled fuel containers be placed in orbit by a launch vehicle where they will remain until they have served their purpose of refueling a space vehicle. This means, therefore, that in order for the maximum amount of fuel to be placed in space and thus be made available for refueling an orbiting spacecraft, the container must be as light as possible. The refueling containers cannot be excessively bulky either since this would require that the launch rocket be increased in size thereby giving rise to additional aerodynamic as well as propellant problems.

From the foregoing it can readily be seen that the prior proposed methods of storing propellants in space, which consist of using a standard type container provided with a bulky, heavy and rigid insulating layer or coating to reduce heat input to the cryogenic propellant fluids, leave much to be desired. Furthermore, since there was no known use for .the gases that were released when the propellant absorbed solar heat, these prior known containers were designed so that when the heat input into the propellant raised the pressure in the container to the design pressure of the container a relief valve opened allowing the propellant to boil-oft into space. For hydrogen propellant approximately one pound of propellant was boiled-oh: for every 190 B.t.u.s of heat that entered the propellant.

Besides the insulation weight being very heavy and thus eflectively limiting the amount of propellant that could be boosted into space and stored for long periods of time, several other disadvantages were inherent with prior known insulated containers. Among these were (1) the side of the container facing or turned toward the source of heat was heated more in localized spots which resulated in a sharp rise in the temperature of the container at that point, thus causing more boil-off than would be caused it the same amount of heat input were distributed over the entire container; (2) heat was absorbed' by those structures such as fuel lines and other hardware exposed to an external source of heat and this absorbed heat was conducted into the propellant; and (3) heat was absorbed by the insulating structure during the light side of an orbit and later absorbed by the propellant on the dark" side of the orbit.

According to the present invention, it has been found that the. above enumerated disadvantages can be eliminated by utilizing a container having a novel insulating jacket for storing cryogenic or other light fuels and gases. This novel container and insulating jacket arrangement consists of an inner container which is employed to hold the fuels being stored and is insulated from any external heat source by a highly flexible, light, inflatable plastic jacket. This jacket is normally stored in a deflated rolledup position in a pocket or channel around the container while the container is not in use or is not exposed to a heating source. Once the container is charged or filled with the liquid to be stored and gases begin to boil-off due to heating occurring, the flexible jacket is simultaneously inflated and unrolled along the container by these escaping gases until it completely surrounds and insulates the container.

Since the inflatable insulating enclosure is to be subjected to a certain amount of meteorite bombardment while in orbit, the jacket preferably contains one or more compartments completely around the container and the compartments are further divided into several sections the entire length of the jacket for isolating any meteorite damage. Furthermore, it has been found that an insulating enclosure formed with a plurality of compartments stacked radially outward from the container will produce a superior insulating action. This is due to the fact that the gases that are just leaving the container and expanding into the compartment will flow along the inner compartment and will be at a lower temperature than the propellant still remaining within the container. Therefore, any heat input into the first compartment of the jacket must come from the next outwardly adjacent compartment and not from the fluid stored within the container.

It is therefore the principal object of the present in vention to provide a novel insulating enclosure for a container.

Yet another object of this invention is to provide a flexible, inflatable enclosure consisting of a plurality of separate compartments for insulating a container.

Yet still another object of this invention is to provide a novel insulating enclosure for a container which utilizes an insulating, flexible baglike enclosure that can be inflated and unrolled along the container.

Yet a further object of this invention is to insulate a container with a flexible, inflatable jacket having a plurality of compartments that are inflated and unrolled along the container by the gases released as the container is heated.

These and further objects and advantages of the invention will become more apparent upon reference to the following description, claims, and the appended drawings wherein:

FIGURE 1 is a view, partially in section, which illustrates a fluid storage container for confining a liquifled gas in outer space with the flexible, inflatable jacket in a stored position;

FIGURE 2 is a section at an enlarged scale through the relief valve and adjacent inflatable insulating jacket shown in its rolled-up or stored position;

FIGURE 3 is a longitudinal sectional view through the container with the flexible, insulating jacket partially inflated and unrolled along the container;

FIGURE 4 is a longitudinal section of the. container substantially fully covered by the flexible insulating jacket; and

, FIGURE 5 is a section at an enlarged scale through the relief valve and adjacent inflated insulating jacket .shown in FIGURE 3.

While for purposes of clarity the instant invention will be described in reference to a storage tank or refueling system for use in outer space, it is to be understood that the invention is equally adapted for numerous other uses. For example, the container and flexible, inflatable insulating jacket would be well adapted for storage of fluids such as water, etc. on earth since the jacket could readily be returned to its stored position when not in use by simply releasing the inflating gas. This would prevent the jacket from being exposed to any weathering or other deterio rating conditions. Furthermore, the inflatable jacket could equally well be used to prevent freezing of tanks or pipes if such were desirable. Other uses and advantages of the instant invention will readily suggest themselves to those persons working in the fluid storage or transporting field.

With continued reference to the accompanying drawings wherein like reference numerals designate similar parts, and with initial attention directed to FIGURE 1, a container means for a fluid or liquified gas, which containing means may be in the form of a storage tank, is indicated generally at 10. This container means includes an inner wall 11 which directly encloses theliquified gases 14 and may be constructed of any suitable material such as plasvalve 29 which is connected to the jacket 18 by suitable means such as. a section of tubing, is shown mounted inside the interstage 17 and connected to the container 10 by tube 12. The relief valve may be of any type that will open when the heat input to the propellant or cryogenic fluid 14 causes 'sufficient boiling to'raise the pressure in the container 16 to a predetermined design pressure.

The overall operation of the relief valve 2t) and insulating jacket 18 may be explained in substantially the following manner. When the propellant pressure, as pictorially represented by the dots 24, builds up to the design pressure of the'container It) the relief valve 2t) opens thereby allowing the gas to flow into the jacket 18. It is assumed that hydrogen is being stored in the'container 1t? and that the design pressure at which the relief valve 7 2 th opens is approximately pounds per square inch.

exist while subject-to a gravitational or centrifugal force although it is to be realized that in orbit the liquid will 7 be in a weightless state and could be anywhere in the container 10. A groove or recess 16 is shown formed completely around an interstage 17 which is secured to the container 10 just above the bulkhead as by welding or brazing and is used to house a heat insulative and radiation-impervious, flexible, inflatable jacket 18 as more clearly seen in FIGURE 2. V V

As shown in FIGURE 2, the flexible jacket 18, which may be formed of any suitable material such as plastic or rubber that will withstand the extreme temperature variations encountered in the particular use for which the container is'designed and which has high heat reflection properties, is stored in a rolled position within'the groove 16. This permits the outer diameter of the storage system to be no greater than that of the container ltl. This is extremely important in certain instance such as when the container is to be shipped in an empty state and it is desirable that a shipping medium having small handling capacity be utilized or where a filled container is to be boosted into space. In the latter case, the reduction in the overall diameter of the container by leaving the inflatable insulating jacket 18 in its stored condition'until the container is in orbit permits the use of a smaller launch vehicle thereby resulting in a larger orbiting payload per pound of launch weight. Furthermore, as long as the jacket 18 remains in its stored position there is little if any danger of it being damaged or ruptured as would be the case if it protruded outwardly or rigidly surrounded the container 16. If necessary, a cap or ring can be used to close the groove is prior to the jacket 18 being inflated thus insuring that the jacket will not be damaged during storage, shipment or, in the case of a rocket firing, during launch.

Numerous devices and methods can be used to inflate the stored jacket 18 including a well-known CO gas bottle or the like. It is preferable, however, in those cases where the container 10 is storing a cryogenic material to inflate the jacket 18 by means of the escaping gas produced as the cryogenic fuel evaporates or boils-off. For insuring the proper operation and inflation of the jacket 18 as the cryogenic fuel 14 boils, a pressure relief The gas flowing from the container 1% through the open relief valve 20 is under sufficient pressure to unroll the flexible jacket 18 out along the container 10 in the manner shown in FIGURE 3. The jacket 18 is so constructed that it extendscompletely around and runs the full length of the container 1t) when it is fully inflated and unrolled.

As shown in FIGURE 4, the flexible jacket 18 can be constructed so that it will not only extend over the container ltl which initially housed it but also over several additional containers and interstages 1% when such is desirable.

The jacket 18 is preferably constructed of a plurality of compartments 263tl that completely surround the container 1t) and are spaced radially outward therefrom as shown in FIGURE 5. Each compartment 26-31? is further subdivided into several sections, some of which are shown at'3248, by flexible partitions 59 for isolating any puncture that might occur in the jacket such as would be caused by meteorite damage. -partments263t} are spaced approximately .250 inch apart with the flow of gas between the compartments and sections being controlled by small apertures 52, which are shown slightly exaggerated for clarity. The flow from the outer compartment 30 into the surrounding medium is controlled by vent apertures 54- that are smaller than the apertures 50 between the compartments for purposes of restricting the gas flow. When desirable the compartments 26-3tl can be partitioned along their longitudinal length so'that the several sections represented at 32-48 will extend the entire length of the jacket 18 rather than sur rounding the container as shown in FIGURE 5.

For purposes of illustrating the superior insulating properties of the inflatable jacket 18, it is assumed that the gas 24 being boiled-oil is at a temperature of 40 degrees Rankine and that the container it) is designed to withstand over 30 pounds/square inch of pressure. When the pressure within the container 1%? reaches 30 pounds/ square inch due to the boiling of the, stored liquid the relief valve 26 will open thereby allowing the gas 24 the. compartment 26 which is under a lower pressure of approximately one pound/square inch, the temperature of the gas will be reduced by approximately 15 degrees Rankine due to the expansion of the gas. Therefore, the gas flow along the inner compartment as depicted by the arrowhead se is at .a lower temperature than the propellant 14 inside the container '15. As is readily apparent, with the temperature inside the compartment 26 at approximately 15 degrees Rankine, while the temperature inside the container 19 is at approximately 40 degrees Rankine, the heat input into the first compartment 26 must come from the center compartment 28. The gas in the center compartment will in turn be required to gain heat from the outer compartment 3 before it can release heat to the inner compartment 26.

. This is true because the pressure within the center compartment 28 is slightly lower than the one pound/square The three com- 7 inch pressure in the first compartment 26, thus permitting the gas from the first compartment to gradually flow through the apertures 52 into the center compartment. Again as the gas flows from an area of higher pressure into an area of lower pressure it will expand and cool to a lower temperature. This process of expanding and cooling will again occur as the gas flows from the center compartment 28 into the outer compartment 30 which exhibits the lowest pressure of the three compartments.

1% is at a temperature of 420 degrees Rankine, then the hydrogen gas within the compartment 39 will gradually absorb heat and expand until the hydrogen vented from the compartment through the aperture 54 is at a temperature of approximately 375 degrees Rankine. This gives a differential temperature of 360 degrees Rankine between the temperature of the gas admitted to the compartment and that vented from the compartment 30. This differential temperature of 360 degrees Rankine is a heat removal factor of 1232 B.t.u.s per pound of hydrogen boiled-oil from the container 1%. This alone, without the reduction gained by the insulating value of the jacket 18, reduces the amount of the liquid boiled-oil by a ratio of 7.484 to 1 over that of a container having only a rigid outer insulating layer that does not utilize the cooling properties of the gas being vented from the container.

ln additon to exhibiting superior insulating properties, the im'latable jacket 12, also possesses numerous other advantages. For example, a more constant and uniform ternuerature is maintained over all surfaces of the container it; during its exposure to the thermal heat reflects ex erienced during orbital flight. This is true since any heating of that portion of the compartments 264d exposed to a source of hea. will result in the gas contained within that portion of the compartments bemg heated and xoanded. This expanding of the heated gas will cause it to dlfluse through apertures 52 into that portion of the compartments not subjected to the heating effect, thus preventing any localized heating. This feature of the insulating jacket 18 also prevents heat from being stored during the so-called light part of an orbit and later absorbed by the stored liquid 14 during the dark part as heretofore has been the case when solid insulating structures were used.

T e flexibility of the insulated jacket 18 is also highly o able since this permits the jacket to readily conform and tightly cover any surface it may be unrolled over. This provides a simple and highly effective method for insuia ting any stmcture or hardware, such as tubing or valves, located adjacent to the container that were heretofore extremely hard to insulate properly.

In certain instances it may be desirable to coat the outer surface 57 of compartment 30 with a heat reflecting material 58 such as a super insulation consisting of layers of foil with spacing material located therebetween. This, needless to say, will provide a means for reflecting most of the solar heat striking the container 19 thereby further increasing the insulating properties of the jacket 18.

From the foregoing, it is readily apparent that this invention provides an inexpensive, novel and unique solutlon to the problem of insulating containers that are to be utilized for such purposes as storing cryogenic fuels and propellants for use by space vehicles. The use of a flexible insulating jacket that is stored in a rolled position until inflated substantially eliminates the weight, storage, shipping installation problems heretofore so prevalent in insulated containers. By constructing the insulating jack-e in various compartments which are inflated by a supercool gas, a structure is produced having heat shielding properties vastly superior to any that can be obtained using other prior known insulation. These compartments also serve to isolate any meteorite or like damage that might occur to the jacket while in use thereby substantially eliminating any chance that the jacket will permit the pres- Assuming that the outer skin 57 of the insulating jacketsurized, supercool gas to escape prematurely. Furthermore, any thermal radiation striking the insulating jacket that is not reflected away will be evenly distributed throughout the jacket thereby preventing any localized heating from occurring.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalents of the claims are therefore intended to be embodied therein.

What is claimed and desired to be secured by a United States Letters Patent is:

1. An insulating structure comprising:

(a) a wall for confining a temperature sensitive material;

(b) a multiplicity of flexible sheets stored in a compacted condition at one point on said wall,

( 1) said sheets being adapted to extend from said stored condition along said wall,

(2) said sheets being disposed in parallel relationship to each other when extended along said wall; and

(0) means for introducing a gaseous material into the voids between said parallel flexible sheets so that said sheets are inflated into spaced relationship to each other thereby forming gas pockets for reducing the transmisison of heat across said sheets.

2. An insulating structure according to claim 1 wherein said flexible sheets are provided with gas passages orientated substantially parallel to said wall and substantially perpendicular to the direction of heat flow across said sheets whereby the variation in thermal conductivity of said insulating structure is reduced.

3. An insulated storage assembly comprising:

(a) a container;

(b) a heat insulative and radiation-impervious jacket substantially surrounding and stored in a compacted condition at one point on said container,

(1) said jacket comprising a multiplicity of thin flexible, radiant heat barrier layers disposed in substantially parallel relation to each other; and

(0) pressure exerting means connected to said jacket for applying a pressure between said heat barrier layers so that said jacket is extended from its stored condition along said container thereby insulating said container, and said layers are spread apart and maintained in a substantially parallel relation thus increasing the insulation characteristics of said jacket.

4. An insulated storage assembly according to claim 3 wherein said heat barrier layers are joined at preselected points to provide fluid passages orientated substantially parallel to said container and substantially perpendicular to the direction of heat flow across said layers whereby the variation in thermal conductivity of said jacket is re duoed.

5. An insulated storage assembly comprising:

(a) a container having substantially rigid walls;

(b) storage means located adjacent to the outside sur face of said rigid walls or" said container;

(0) a heat insulative and radiation-impervious inflatable medium stored within said storage means,

(1) said heat insulative medium being adapted to extend from said storage means along the outside surface of at least a portion of said rigid walls of said container when said heat insulative medium is inflated; and

(d) means for inflating said heat insulative medium.

6. An insulated storage assembly according to claim 5 wherein said heat iusulative medium surrounds and substantially covers the outside surface of said rigid Walls of said container when said heat insulative medium is inflated.

'7. An insulated storage assembly according to claim wherein ,said heat insulative medium is stored in a rolled condition within said storagemeans.

8. An insulated storageassembly for the holding materials at low temperature, comprising;

(a)a container for holding such materials; 7

(b) storage means carried near one endof said container;

(c) a heat insulative and radiation-impervious inflatable jacket stored within said storage means,

(1) said jacket being adapted to extend from said storage means and. substantially completely cover said container when said jacket is inflated,

' (2 said jacket comprising a multiplicity of thin flexible heat barrier layers disposed in substantially parallel relation to eachother; and

' '(d) means for applying gaseous pressure to said jacket so that said jacket is inflated thereby being extended from said storage means to substantially cover said container,

(1) said heat barrier layers being maintained in a parallel spaced relation by said gaseous pressure thereby forming gas pockets for reducing the transmission of heat across said jacket. 9. An insulated storage assembly according to claim 8 wherein said heat barrier layers are joined at predetermined points to provide a plurality of gas passages orientated substantially parallel to said container and substantially perpendicular to the direction of heat flow across said layers whereby the variation in thermal conductivity of said jacket is reduced.

10. An insulate materials at low temperature, comprising:

(a) a container for holding such materials;

(b) storage means carried by said container,

(1) grooved means formed in said storage means;

(c) a heat insulative and radiation-impervious inflatable jacket stored within said grooved means,

(1) said jacket being adapted to extend from said grooved means and substantially completely cover said container when said jacket is inflated,

(2) said jacket comprising a multiplicity of thin flexible heat barrier layers disposed in substantially parallel relation to each other; and

' (a?) means connected between said container and said jacket for applyin' gaseous pressure generated within said container to said jacket so that said jacket is inflated and extendedrfrom said grooved'means 'to substantially cover said container, V

(1) said heat barrier layers being maintained in a parallel spaced relation by said gaseous pressure thereby forming gas pockets for reducing the transmission of heat across said insulating 7 jacket. V j

11. An insulated storage assembly according to claim 10 wherein said means connected between said container and said jacket is a valve which operates when the gaseous pressure generated within said container exceeds a preselected value.

12. An insulated storage assembly according to claim 10 wherein said heat barrier layers are joined at predetermined points .to provide a plurality of gas passages oriented substantially parallel tosaid container and substantially perpendicular to the direction of heat flow across said layers whereby the variation in thermal conductivity of said jacket is reduced.

13. An insulated storage assembly according to claim 10 wherein said jacket is stored in a rolled condition within said grooved means.

14. An insulated storage assembly for the holding of cryogenic materials, comprising:

(a)"a container for holding such'rnaterials;

storage assembly for the holding of 'tainer means, 7

(1) said storage means having grooved means formed in its outer surface which extends substantially completely around said storage means; (0) a heat insulative and radiation-impervious inflatable jacket stored in a rolled'condition within said grooved means. (1) said jacket being adaptedto extend from said grooved meansand un-roll along the outer suriace of said container thereby substantially covering said container when a gaseous pressure 7 is appliedto said jacket; (d) valve means 'o-peraitively connected between said container and said jacket, 7

i (1) said valve means) being adapted to operate when the pressure of the gas produced by the evaporation of the cryogenic material stored within said container exceeds a preselected value thereby permitting said gas to flow into and inflate said jacket. 15. An insulated storage assembly for the holding of ryogenic materials, comprising:

(a) container means for holding said cryogenic material;

(b) storage means mounted on one end of said con tainer means,

(1) said storage means having a recess formed around its outer surface;

(c) a heat insulative and radiation-impervious inflatable jacket stored in a rolled condition within said recess,

(1) said jacket being adapted to extend from said grooved means and unr-oll along the outer surface of said container means thereby substantially covering said container when a gaseous pressure is applied to said jacket,

(2) said jacket comprising at least a first, second and third inflatable insulating compartment disposed in substantially parallel relation to each other and stacked perpendicularly to the wall of said container when said jacket is unro'lied along said container,

(A) each of said insulating compartments consisting of at least a first and second connected by a piurality of apen.

l V tures; and (d) a pressure relief valve operatively connected between said container means and said first insulating compartment,

(1) said pressure relief valve being adapted to open when the pressure of the gas produced by the evaporation of the cryogenic material stored value, within said container exceeds a preselected (A) the opening of said valve permitting said gas to fiowfrom said first insulating compartment into said second insulating compartment and then into said third insulating compartment through said interconnected apertures,

(B) the internal pressure of each of said insulating co'rnpartments being maintained at a progressively lower value whereby said value whereby said gas expands as it flows through said insulating compartments for reducing the transmission of heat across said jacket,

25 (C) said third insulating compartment having vent apertures for-med therein for permitting the gradual escape of said gaseous pressure from said iacket.

16. An insulated storage assembly according to claim 15 wherein a layer of insulation is carried on the outer surface of said jacket.

17. An insulated storage assembly according to claim 16 wherein said container means is a @lurality of storage tanks.

References Cited by the Examiner UNITED STATES PATENTS 662,217 11/00 Brady 6245 10 Spiegelhalter. Davison.

Rice et a1. 62-239 Morrison.

Vandenberg.

Irvine 62-45 FOREIGN PATENTS Great Britain.

ROBERT A. OLEARY, Primary Examiner. 

1. AN INSULATING STRUCTURE COMPRISING: (A) A WALL FOR CONFINING A TEMPERATURE SENSITIVE MATERIAL; (B) A MULTIPLICITY OF FLEXIBLE SHEETS STORED IN A COMPACTED CONDITION AT ONE POINT ON SAID WALL, (1) SAID SHEETS BEIND ADAPTED TO EXTEND FROM SAID STORED CONDITION ALONG SAID WALL, (2) SAID SHEETS BEING DISPOSED IN PARALLEL RELATIONSHIP TO EACH OTHER WHEN EXTENDED ALONG SAID WALL; AND (C) MEANS FOR INTRODUCING A GASEOUS MATERIAL INTO THE VOIDS BETWEEN SAID PARALLEL FLEXIBLE SHEETS SO THAT SAID SHEETS ARE INFLATED INTO SPACED RELATIONSHIP TO EACH OTHER THEREBY FORMING GAS POCKETS FOR REDUCING THE TRANSMISSION OF HEAT ACROSS SAID SHEETS. 